This invention relates to syringe tip locking assembly for use with a syringe tip in a three-way dental handpiece assembly, and more particularly to a syringe tip locking assembly that comprises a multi-component assembly of an adaptor, a gripping member and a screw down locking cap to hold a syringe tip securely in place on a tapered male member in the adaptor when the adaptor is mounted in the handpiece of a three-way dental syringe assembly.
U.S. Patent No. 5,049,071 (Davis et al.) discloses a disposable dental syringe tip made of plastic material. This patent also discloses various adaptors that can be used to attach the disposable syringe tip to the handpiece of a three way dental syringe assembly. The disclosure of this U.S. Pat. No. 5,049,071 is incorporated herein by this reference. Additionally, U.S. application Ser. No. 07/596,987, filed Oct. 11, 1990, entitled "Dental Syringe Tip and Adaptor", now U.S. Pat. No. 5,192,206, contains additional disclosure relating to adaptors for use in three way dental syringe assemblies and the disclosure of this patent is incorporated herein by this reference.
The use of disposable plastic syringe tips has become quite widespread in light of the serious concern about the rising incidence of communicable diseases such as hepatitis and acquired immune deficiency syndrome. Dentists are taking extreme care to prevent the transmission of germs (viral or bacteria) from one patient to the next. With the conventional metal syringe tips, it was necessary to clean and sterilize the tip after each patient use. In this context, cleaning means the complete removal of all impurities and foreign matter from both the outside and the inside of the syringe tip. Cleaning must be performed first because while it is possible to clean an item without sterilizing it, it is not possible to sterilize an item without thoroughly cleaning it first. The American Dental Association states that all patient debris and bodily fluids must be removed from the instruments and surfaces before sterilization and disinfection.
The standard design of a metal syringe tip involves two metal tubes, the central metal tube completely surrounded by an outer metal tube. Fabricating a conventional metal tip results in surface defects at the junction point where the two tubes are joined together. The metal used in these tips is brass which is then chrome plated on its exterior surface. The interior brass material is extremely susceptible to corrosive deterioration. The rough interior surfaces promote the harboring of bacterial plaques and pathogens. A university study has proven that it is virtually impossible to clean the interior surfaces of a metal tip. It is axiomatic in sterilization technique, "if you can't clean it, you can't sterilize it." The processing of metal tips in the dental environment makes their current use an unacceptable answer to the problems of infection control. The disposable plastic tip is the surest way to avoid cross-contamination from patient to patient.
An analogous situation occurred with the hypodermic needle. Hypodermic needles were routinely sterilized until the early 1950's. A hepatitis epidemic, traced to contaminated hypodermic needles, advance the development of the disposable needle. Because it was impossible to preclean blood and other body fluids from the internal surface of a hypodermic needle, the need to develop a cost effective disposable needle became critical. These same concerns exist in the passageways of air/water syringe tips. Now that disposable tips are available for the air/water syringe, they will become the standard, and thus, eliminate the possibility of cross-contamination from patient to patient.
The plastic syringe tip receives air and water under pressure. It is necessary to securely hold the plastic syringe tip in the appropriate adaptor. As shown in FIG. 8 of U.S. Pat. No. 5,049,071, the end of the syringe tip is press fit over a tapered male member. Due to discrepancies and tolerances in the extrusion process, the syringe tip can partially disengage from the adaptor. This results in an inadvertent mixture of air and water when not desired.
It is an object of the present invention to provide a syringe tip locking assembly that securely holds the syringe tip in the adaptor and prevents inadvertent loosening of the syringe tip so that the air and water supply are totally separate.
It is a feature of the present invention to provide a syringe tip locking assembly that includes an adaptor, a gripping member and a locking cap. The gripping member fits over the tapered male member on the inside of the adaptor body. The gripping member includes a plurality of gripping fingers that engage the syringe tip when the locking cap is screwed into locking position. The locking cap screws over the adaptor to effect the tightening of the gripping fingers into the syringe tip and at the same time pulls the syringe tip onto the end of the tapered male member.
It is an advantage of the present invention that the plastic syringe tip will be securely held in place in the adaptor so that the air and water supply is at all times fed through the appropriate passageways in syringe tip and to inhibit the inadvertent loosening of the syringe tip from the adaptor to prevent the syringe tip from being dislodged from the handpiece.
Other objects, features and advantages will become apparent when the detailed description and drawings of the present invention are considered.